Hmmm, I'm not familiar with a "Material Import function" in Corona or C4D. Usually models, you download from the internet, will will have their own Tex folder, but the paths are not localized so the file cannot find the textures. You can move the texture files so they are in the same folder as the C4D file, it will find them. You would probably copy the textures to your main Tex folder that your C4D points to. Then, when you import your model, the materials will be there.